Effect of adsorbent particle size distribution on breakthrough curves for molecular sieve columns

Moharir, Arun S.; Kunzru, Deepak; Saraf, Deoki N.

doi:10.1016/0009-2509(80)85017-2

Cited by 20 publications

(6 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These calculated results are for assemblies of aggregates of one size only. Moharir et al (1980) and Rasmuson (1985a,b) have considered the process for a distribution of sizes. Tanton et al (1988a) used the analysis for spherical aggregates to predict the observed leaching from clods of clay soil and demonstrated the leaching of salts from restructured saline clay soils (Tanton et al, 1988b).…”

Section: Mode 1: Macropore and Micropore Regions Both Fully Saturatedmentioning

confidence: 99%

Aspects of transport processes in aggregated soils

Youngs

Leeds‐Harrison

1990

Journal of Soil Science

View full text Add to dashboard Cite

The way in which water and solutes move in aggregated soils depends on the mode of saturation of the pore space that is made up of the micropore region within the aggregates and the macropores surrounding them. When both regions are saturated, a hydraulichead gradient causes water to flow preferentially in the macropores with little flow within the aggregates, so that movement of solutes into or out of the aggregates is mainly by diffusion caused by the difference between the solute concentrations of the water in the two regions. When macropores full of water surround unsaturated aggregates, water is imbibed by the aggregates giving rise to convective movement of solutes with the moving water. When the macropores are empty, the aggregates become almost isolated so that redistribution of water and solutes occurs only within the aggregates with very little transport of water and solutes between them. The movement of water and solutes in the micropore region within the aggregates can be considered to behave as if in a continuum, and can be described by Darcy's law and the dispersion equation, with boundary conditions imposed by conditions in the macropores.These physical considerations of transport behaviour in aggregated soils can be used to give guidance on soil management practices concerning drainage and leaching.

show abstract

Section: Mode 1: Macropore and Micropore Regions Both Fully Saturatedmentioning

confidence: 99%

Aspects of transport processes in aggregated soils

Youngs

Leeds‐Harrison

1990

Journal of Soil Science

View full text Add to dashboard Cite

show abstract

“…The PSD effects on the prediction of sorption uptake curves in a batch system have been investigated by Ruthven and Loughlin (1971) and later by Moharir et al (1980a) in an attempt to resolve the discrepancy between the theoretical and experimental sorption uptake curves. In those studies, the effects of a combined average particle size and size distribution were examined, and therefore the effects of the PSD alone might have been overestimated.…”

Section: Introductionmentioning

confidence: 99%

“…In those studies, the effects of a combined average particle size and size distribution were examined, and therefore the effects of the PSD alone might have been overestimated. The consideration of a PSD in the mathematical modeling for chromatographic columns appears to be first reported by Moharir et al (1980b) on the prediction of breakthrough curves from a zeolite column using a swelling crystal model to indirectly describe the zeolite crystal PSD. Since then, incorporating a PSD in the mathematical modeling has been reported by many investigators to determine adsorption and diffusion parameters (Hsu and Haynes, 1981;Bonifaceand Ruthven, 1985;Hyun and Danner, 1985;Fu et al, 1986).…”

Section: Introductionmentioning

confidence: 99%

Analysis of liquid chromatography with nonuniform crystallite particles

Yue

1990

AIChE Journal

View full text Add to dashboard Cite

A mathematical analysis for the pulse responses of a liquid chromatographic column packed with crystal powders having a particle size distribution and a nonlinear adsorption isotherm is presented. The mathematical model is solved numerically by the orthogonal collocation method. Based on the parametric analysis of the model, the effects of a symmetrical and moderately asymmetric PSD on the LC responses are shown to be negligible in comparison with the effects of other parameters, such as isotherm nonlinearity, whose effects are much more profound. The simulated responses are compared with the experimental response data for an LC column packed with silicalite crystals, and a good agreement is found between the theoretical and experimental results. Using the nonlinear LC model, the simultaneous determination of nonlinear adsorption isotherms and intraparticle diffusivities from LC pulse responses is demonstrated for liquids in porous adsorbents. Y. S. Lin Y. H. Ma Chemical Engineering DepartmentWorcester Polytechnic Institute Worcester, MA 01609 IntroductionWith extensive applications of chromatographic techniques in bulk separations, purifications and physico-chemical parameter determinations (Conder and Young, 1979;Ruthven, 1984;Wankat, 1986), many mathematical models have been developed and solved for the mass transfer in chromatographic columns packed with porous particles. These studies include: the analytical solutions for the problems of chromatography with simpler mathematical models which neglect either axial dispersion or intraparticle diffusion (e.g., Rosen, 1952;Masamune and Smith, 1964); the modeling and analytical solutions for chromatography with the consideration of both intraparticle diffusion and axial dispersion (Deisler and Wilhem, 1953; Rasmuson and Nerenieks, 1980;Rasmuson, 1981); and the development of many more complex models for chromatography such as the macro-micropore diffusion models for the chromatographic columns packed with bidisperse structured adsorbents (Ma and Mancel, 1973;Hashimoto and Smith, 1973; Haynes and Sarma, 1973). Most of these models, however, were developed for gas chromatographic columns under the assumption of a linear adsorption isotherm.Nonlinear adsorption isotherms are more frequently encountered in liquid chromatographic systems. The mathematical

show abstract

“…The reaction rate constant and the particle tortuosity factor were estimated from experiments C2 to C4 (conducted with crushed particles) using eqs. (9) to (14). The estimated values are given in Table 9, together with the 95% confidence interval.…”

Section: C4mentioning

confidence: 99%

Tortuosity and mass transfer limitations in industrial hydrotreating catalysts: effect of particle shape and size distribution

Kolitcheff

Jolimaître

Hugon

et al. 2018

Catal. Sci. Technol.

View full text Add to dashboard Cite

The tortuosity factor of γ-alumina supports and catalysts used in hydrotreating applications was evaluated in liquid phase with three different techniques: Pulse Field Gradient-NMR (PFG-NMR), Inverse Liquid Chromatography (ILC) and catalytic experiments in a batch reactor. In order to satisfy the specific experimental constraints associated to each technique, tortuosity factor values were evaluated in a wide range of operating conditions: temperature was varied from 25°C to 340°C, catalyst particles were used as-synthesized (trilobe extrudates) or crushed, the liquid composition was either pure toluene, n-heptane/squalane mixtures, or squalane/2,5-bis-(octadecyl)thiophene mixtures. It is demonstrated that not taking into account both the shape factor and the size distribution of the particles can lead to significant errors on the tortuosity factor value. For both parameters, the optimal mean spherical radius depends on the contribution of internal diffusion to the overall performance. When internal diffusion is the limiting step, a new expression for the mean radius of distributed particle is proposed and validated by comparison between ILC and PFG-NMR results. This expression is transposable to any catalytic system, making it possible to measure tortuosity factors using either microscopic or macroscopic methodologies. Moreover, the tortuosity factors obtained with ILC and NMR are in good agreement with the one estimated from the catalytic experiments, showing that mass transfer parameters can be extrapolated from non-reactive to reactive conditions.

show abstract

Effect of adsorbent particle size distribution on breakthrough curves for molecular sieve columns

Cited by 20 publications

References 10 publications

Aspects of transport processes in aggregated soils

Aspects of transport processes in aggregated soils

Analysis of liquid chromatography with nonuniform crystallite particles

Tortuosity and mass transfer limitations in industrial hydrotreating catalysts: effect of particle shape and size distribution

Contact Info

Product

Resources

About